PATHOLOGY AND MORBID ANATOMY.--The perichondrium of the larynx is diseased comparatively oftener than that of any other region of the body; which, aside from other causes, is partly due to the fact that the laryngeal cartilages become with increasing age normally vascular and ossified. The morbid process never affects at one time the whole of the cartilaginous framework of the larynx, and usually only one cartilage, or even only a limited portion of one cartilage, except in the case of the cricoid and arytenoid, which are sometimes together implicated. Perichondritis does not spread easily. The cricoid is most frequently affected, next the arytenoid, far less often the thyroid, and exceedingly rarely the epiglottis. As already remarked, the inflammation of cartilage and perichondrium {119} has a great tendency to suppuration--occasionally, though rarely, proliferation and hypertrophy; or, on the other hand, and more frequently if the inflammation is a slowly progressing one, the processes leading to ossification take place. The suppurative stage follows the inflammatory quickly unless the latter has been comparatively very slight. A great abundance of pus collects between the cartilage and its investing membrane. As the former is thereby denuded and separated from its nutritive vessels, it must become necrotic. Exfoliated pieces of cartilage are generally found in the abscess. Caries of adjacent tissues is apt to take place, and oedema of the surrounding connective tissue, and sometimes far-reaching destruction, before the perichondrium bursts or becomes destroyed over a large extent. In cricoid perichondritis, the plate mainly being affected, the abscess projects mostly toward the oesophagus and the trachea, or it points outwardly when the narrow portion is involved; the opening when the abscess has burst is frequently large, and shows a portion of the necrosed cartilage; sometimes there are a number of perforations. In arytenoid perichondritis the abscess bulges either into the interior of the larynx or into the adjacent pyriform sinus; bursting usually occurs at the posterior portions of the ventricular folds or near the posterior vocal process, and the undermined edges may disclose the dead cartilage. In thyroid perichondritis either the interior of the larynx, the pyriform sinus, or the outside of the neck is encroached upon.